The present invention relates to an apparatus used in making adjustments in the circumferential setting of a rotating element of a machine for operating on a moving web. More particularly, the invention relates to an apparatus that measures the rotational position of one such rotating element with respect to the position of another element, and updates and displays the measurement as adjustments are made.
Conventional web presses used in the manufacture of business forms combine a plurality of sections or stations housing various machines for printing, numbering, perforating, slitting, punching holes or the like on a moving paper web. These operations are all performed by various machines, each typically including at least two rotating cylinders between which the web is passed during the manufacture of the forms. The particular relative locations of the features of each form that result from the different operations on the web are dependent upon both the lateral and circumferential setting of the cylinders of each machine. Thus, depending upon the needs of a particular job, it is necessary to adjust these settings prior to running of the press to ensure that each of the operations is performed in the proper location. Moreover, it may become necessary during the press run to adjust the settings of the cylinders of the various machines, to correct for any mismatching of the different operations.
Similar considerations apply to other multi-operation equipment containing machines for operating on a moving web. For instance, in a collator used for assembling a number of individual webs into a single multi-layer business form, various machines for layering, perforating, punching and the like of a multi-layer web are used. The cylinders of such machines require both initial and subsequent adjustments of their lateral and circumferential settings to ensure proper location of the various operations.
In equipment utilizing a series of rotating cylinders, various methods and devices are known for making adjustments to the circumferential setting of the cylinders, both while the cylinders are being rotated and while the cylinders are stopped. In order for the operator of the adjustment mechanism to properly make such adjustments, however, some means of measuring the circumferential setting of the cylinders with respect to each other must be provided.
In U.S. Pat. No. 3,963,902, issued June 15, 1976, to Dowd, a method and apparatus for providing such measurements is disclosed. A plurality of cylinders is used, each driven from a common drive train through individual differential devices, each device having an input connected to a reversible adjustment motor. An electric pulse generator is driven by the drive shaft, and supplies a plurality of signals in response to rotation of the drive train to a pulse counter. Each cylinder is provided with a pulse emitter for generating a single pulse in response to each revolution of the cylinder. One cylinder is designated as the reference cylinder, and the pulses from its emitter are supplied to the counter as start signals. A stop signal is also supplied to the counter, which is selected from the pulse emitter signals from any of the remaining cylinders. After rotation of the reference cylinder signals the counter to begin counting, the pulses supplied from the drive train generator are counted until the pulse emitter on the particular selected cylinder supplies a stop signal to the counter. The number of accumulated pulses is displayed by the counter, and represents the difference in rotational position between the reference cylinder and the particular cylinder under consideration. Upon receipt of the following start signal, the counter is cleared and the count is repeated.
It can be seen, however, that the apparatus disclosed in the Dowd patent requires that the press be operated at running speed to be effective. In the event adjustments are desired to be made while the press is being run at inching speed, it will be necessary to wait for the cylinders to complete one full revolution for the updated count reflecting the adjustment to be displayed. Accordingly, as the adjustment is being made, the operator has no indication of the size or effectiveness of the adjustment. Thus, it may often be necessary to repeat the adjustment process a number of times before the desired adjustment is made.
Further, it can be seen that the Dowd apparatus cannot be used for making circumferential adjustments with the press stopped. In the event such adjustments are desired, it will be necessary to start and run the press for at least one revolution of the cylinders following each actuation of the adjustment motor, again with the operator having no indication at the time of adjustment of the actual magnitude of the adjustment made.
What is needed, therefore, is an apparatus and method for measuring the circumferential setting of a rotating element of a machine for operating on a moving web. Such an apparatus and method should be usable regardless of whether the machine is being operated at running speed, inching speed, or is stopped. Such an apparatus and method should further provide a means for displaying the measurement, and should update the measurement and its display as circumferential adjustments are made.